The present invention relates to a telescopic device, more particularly, to a telescopic device with a firm positioning effect which can be applied a scratch awl, a drilling bar, a screw, a ball-pen and the like for achieving a better positioning effect as well as ease of retraction.
FIG. 20 shows the structure of a conventional drill bar and FIG. 21 shows a conventional scratch awl. Neither the drill bar nor the scratch awl is equipped with a telescopic design so that the pointed end thereof could easily injure the skin of the user when they are carried on the pocket of their clothes of the user.
FIG. 22 shows the cross-sectional view of a conventional ball-pen. By pressing a button rod (d), a sliding pin (d1) moves along a channel (b) and is positioned at a positioning slot (c) so that the pen point (f) extends from the pen tube (a), and the ball-pen is ready for use (see FIG. 23). FIG. 24 shows the cross-sectional view of another conventional ball-pen. When a button rod (d) is pressed, the position point (c1) of a pin (c2) moves to a position slot (a1) and the pen point (f) of the ball-pen is exposed for use (see FIG. 25). These two types of conventional ball-pens have a common disadvantage that a firm positioning might not be achieved so that the pen point (f) could easily retract back to the inside of ball-pen during use. The structure of a third conventional ball-pen is shown in FIGS. 26 and 27 and is equipped with the design of a ratchet device. During use of the ball-pen, however, a cam body (d1) which abuts against the positioning portion (b2) might move from it so that the pen point (f) draws back inside the pen tube (a). FIGS. 28 and 29 show the cross-sectional view of a fourth conventional ball-pen. By pressing the rod (d), a pin (k) is urged to slidably move into a positioning slot (b3) disposed at the pen tube (a) of the ball-pen while the push rod (k1) pushes the pen point (f) so as to be exposed outside the body of the ball-pen for use. Such a design has the disadvantage that the pin (k) easily deforms and moves away from the positioning slot (b3) so that the pen point (f) retracts into the pen tube (a).